Analysis by: Julie Anne Cabuhat
ALIASES:

Ransom.HiddenTear.MSIL (Malwarebytes), Trojan-Ransom.HiddenTear (Ikarus), Ransom:MSIL/Ryzerlo.A (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware, Downloaded from the Internet

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It adds certain registry entries to disable the Task Manager. This action prevents users from terminating the malware process, which can usually be done via the Task Manager.

  TECHNICAL DETAILS

File Size: 113,664 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 01 Jan 2017
Payload: Disables services, Encrypts files, Renames files

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Windows Search = {malware path}\{malware filename}.exe

Other System Modifications

This Trojan adds the following registry entries to disable the Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = 1

Other Details

This Trojan encrypts files with the following extensions:

  • .txt
  • .doc
  • .docx
  • .xls
  • .xlsx
  • .ppt
  • .pptx
  • .odt
  • .jpg
  • .png
  • .csv
  • .sql
  • .mdb
  • .sln
  • .php
  • .asp
  • .aspx
  • .html
  • .xml

It renames encrypted files using the following names:

  • {Original file name and extension}.locked

NOTES:

The ransomware encrypts files located in the following location:

  • %Desktop%

    The ransomware displays the following ransom note:

    •   SOLUTION

    Minimum Scan Engine: 9.850
    FIRST VSAPI PATTERN FILE: 13.132.06
    FIRST VSAPI PATTERN DATE: 02 Jan 2017
    VSAPI OPR PATTERN File: 13.133.00
    VSAPI OPR PATTERN Date: 03 Jan 2017

    Step 1

    Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

    Step 2

    Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

    Step 3

    Restart in Safe Mode

    [ Learn More ]

    Step 4

    Delete this registry value

    [ Learn More ]

    Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

     
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Windows Search={malware path}\{malware filename}.exe

    Step 5

    Enable Registry Editor, Task Manager, and Folder options

    [ Learn More ]
    By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

    Step 6

    Restart in normal mode and scan your computer with your Trend Micro product for files detected as RANSOM_HIDDENTEARTRANSOM.A . If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

    Step 7

    Restore encrypted files from backup.


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